1. Field of the Invention
The present invention relates to oil and gas well drilling and to the disposal of bore hole cuttings and like solids, used drilling fluids and waste water on drilling rigs. The present invention more particularly relates to the collection, loading, and disposal of bore hole cuttings.
2. General Background
Washing shale cuttings extracted from oil well bore holes and returning the cleaned cuttings to the soil or water mass surrounding a drilling rig was once a widely accepted practice in the drilling industry. However, government environmental regulations have caused many oil well operators to look for alternate methods of disposing of the cuttings since it is often difficult to clean the cuttings sufficiently to meet the government standards.
Typically shale cuttings mixed with drilling fluids are extracted from oil well bore hole during drilling operations. As the cuttings and drilling fluids come out of the bore hole, they are cycled through solids separators and solids removal equipment, commonly known in this industry as shale shakers and hydroclone mud cleaners, which separates the shale cuttings from the drilling fluids. As used herein, the term solids separator refers to any of a class of machines which are used on oil well drilling rigs to separate drill cuttings from the drilling mud stream, including e.g. shale shakers, hydrocyclone mud cleaners, and the like. A trough slanted at an angle connects the solids removal equipment to a cutting water. A wash solution of water and a special soap mixture circulate through the trough. Shale cuttings separated from the drilling fluids are released from the solids removal equipment into the trough. The wash solution mixes with the shale cuttings and forms a slurried composition which is carried by gravitational forces to a cuttings washer. The cuttings washer receives the slurry, swirls it around to clean the cuttings and pumps the slurry over a high-speed shaker which separates the cuttings from the wash solution. Cleaned cuttings from the high-speed shaker are either dumped over the side of the rig into the environment or loaded into containers to be transported to a disposal site.
Washing shale cuttings or solids has a number of disadvantages, including those set forth below. First, the equipment requires constant supervision and maintenance to insure the proper cleaning of the cuttings. Second, the cleaned cuttings often do not meet government environmental regulation thus exposing oil well operators to the possibility of large fines for polluting the environment and even larger costs for cleaning water bottoms in the area of the drilling rig. Third, maintaining the proper composition of the wash solution is difficult. Frequently small amounts of oil-based liquids are discharged into the solids removal equipment along with the shale cuttings. The oil-based liquids rapidly deteriorate the wash solution. Additionally, the cuttings are often bentonic or clay-bearing in nature. These cuttings react with the wash solution reducing its efficiency. Wash solutions contaminated by oil-based liquids and bentonic cuttings must be replaced, thus increasing the costs of drilling the oil well. Fourth, expensive drilling fluids not separated from the cuttings in the solids removal equipment are dispersed into the wash solution and cannot be salvaged and reused. Fifth, the was method generates two by-products, large amounts of dirty water and sludge, which must be stored on the rig until they can be transported to a disposal site. The sludge accumulates in the bottom of the washer tanks and in the dirty water holding tanks. Its consistency is such that it is difficult to move. Since it clogs pumps and hoses it often must be shoveled into containers manually.
Some oil well operators, distrustful of the effectiveness of the wash system and concerned about the environment have chosen not to return the washed cuttings to the waters surrounding drilling rigs. They use the cuttings washer to consolidate the cuttings, which are then deposited into containers for transportation to disposal sites.
The methods of filling the containers with shale cuttings are primitive. The basic rig design with its limited space and large equipment which obstructs available space make it difficult to place large solids transport containers near the solids removal equipment and the cuttings washer. Presently, cuttings are manually shoveled into barrels and similar smaller containers which are sometimes emptied into larger containers for transportation to the disposal site. The shoveling and dumping of cuttings into large containers is not only messy, but also hazardous and labor intensive. Additionally, there are no means for recovering the drilling fluids discharged from the solids removal equipment.
An assortment of containers are now being used to transport the cuttings to the disposal site. The containers include plastic bags, barrels, metal boxes and tanks. Often the containers do not have appropriate closing means and the cuttings spill or leak during transit to the disposal site, thus obligating the oil well operator to the additional expense of cleaning the mess.
Methods for transportation material and people from location to location through the use of conveyor or moving stairways are used in various commercial establishments. Some conveyor systems and conveyor housings have been patented. Several of those patents are noted hereinafter.
U.S. Pat. No. 4,051,948 issued to Walter James Sackett, Sr. shows a dual conveyor system enclosed in a housing which protects the material to be moved from moisture and dust and prevents the material from spilling during transit.
U.S. Pat. No. 2,343,762 issued to John Jay Hankin discloses a screen type conveyor having a side guard along the edges of the conveyor which prevents material from falling off the side edges of the conveyor in transit.
U.S. Pat. No. 2,634,850 issued to Hans E. Hansen shows an apparatus which is used to clean continuously the drip pans of moving stairways.
U.S. Pat. No. 2,617,515 issued to Otto Hobnecker shows a device for cleaning the dirt and dust which accumulates on the interior of the supporting structure of a moving stairway.
U.S. Pat. No. 3,315,782 issued to Richard T. Tyndall discloses a valve for conveyor housings which facilitates cleaning th interior of the housing.
U.S. Pat. No. 4,026,603 issued to Werner Georg shows a conveyor system comprising a series of interconnectible pans arranged end to end having a scraper-chain assembly which circulates through the conveyor sections to move materials.
U.S. Pat. No. 4,170,293 issued to David R. Campell shows a housing for a conveyor having exterior structural supports.
U.S. Pat. No. 3,878,936 issued to Fred William Niggemyer teaches a conveyor housing having a bottom portion and a top portion fastened together by bolts and toggle type C-clamps.
U.S. Pat. No. 3,147,852 issued to W. Hanson, Jr. shows a conveyor cover which protects material being conveyed from the elements.
The foregoing patents show some features of conveyors and conveyor housings used in the transportation of people and materials from location to location. These devices however fail to disclose the method and apparatus of the present invention which solves the problem of well cuttings disposal in a simple, straightforward and easy manner.